U.S. patent application number 13/705795 was filed with the patent office on 2013-06-06 for methods for reducing the blood priming volume and membrane surface area in microfluidic lung assist devices.
This patent application is currently assigned to The Charles Stark Draper Laboratory, Inc.. The applicant listed for this patent is The Charles Stark Draper Laboratory, Inc.. Invention is credited to Jeffrey T. Borenstein, Joseph L. Charest, Alla Epshteyn, James C. Hsiao, Ernest S. Kim, Tatiana Kniazeva, Vijaya Kolachalama.
Application Number | 20130144266 13/705795 |
Document ID | / |
Family ID | 47352068 |
Filed Date | 2013-06-06 |
United States Patent
Application |
20130144266 |
Kind Code |
A1 |
Borenstein; Jeffrey T. ; et
al. |
June 6, 2013 |
METHODS FOR REDUCING THE BLOOD PRIMING VOLUME AND MEMBRANE SURFACE
AREA IN MICROFLUIDIC LUNG ASSIST DEVICES
Abstract
A device and method for oxygenating blood is disclosed herein.
The device includes a plurality of passive mixing elements that
causes a fluid to mix as it flows through the device. The passive
mixing elements continually expose new red blood cells to the
portion of the flow channel where oxygenation can occur.
Accordingly, in some implementations, the device and method uses
less blood to prime the device and allows for the oxygenation of
blood with a substantial shorter flow channel when compared to
conventional oxygenation methods and devices.
Inventors: |
Borenstein; Jeffrey T.;
(Newton, MA) ; Charest; Joseph L.; (Cambridge,
MA) ; Hsiao; James C.; (Watertown, MA) ;
Kniazeva; Tatiana; (Boston, MA) ; Kim; Ernest S.;
(Cambridge, MA) ; Epshteyn; Alla; (Brookline,
MA) ; Kolachalama; Vijaya; (Cambridge, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Charles Stark Draper Laboratory, Inc.; |
Cambridge |
MA |
US |
|
|
Assignee: |
The Charles Stark Draper
Laboratory, Inc.
Cambridge
MA
|
Family ID: |
47352068 |
Appl. No.: |
13/705795 |
Filed: |
December 5, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61567104 |
Dec 5, 2011 |
|
|
|
Current U.S.
Class: |
604/522 ; 422/48;
435/2 |
Current CPC
Class: |
A61M 1/1698 20130101;
A61M 2206/20 20130101 |
Class at
Publication: |
604/522 ; 422/48;
435/2 |
International
Class: |
A61M 1/16 20060101
A61M001/16 |
Claims
1. A microfluidic oxygenation device comprising: a first polymer
layer defining a first oxygen flow channel therein; a second
polymer layer defining a first blood flow channel therein, the
first blood flow channel overlapping the first oxygen flow channel,
and the first blood flow channel further comprising at least one
passive mixing element formed on or within a first wall of the
first blood flow channel, the passive mixing element configured to
redistribute a fluid flowing through the first blood flow channel
within the channel; and a membrane separating the first oxygen flow
channel and the first blood flow channel at the overlapping
portions of the channels, the membrane allowing communication
between the first oxygen flow channel and the first blood flow
channel.
2. The device of claim 1, wherein the passive mixing element is one
of a straight ridge, an angled ridge, a chevron canal, a dome, a
cone, a pit or a post.
3. The device of claim 1, wherein a first fluid flows through the
first oxygen flow channel and a second fluid flows through the
first blood flow channel.
4. The device of claim 3, wherein the first fluid is oxygen and the
second fluid is deoxygenated blood.
5. The device of claim 1, wherein the height or depth of the
passive mixing element is less than about 30% of the height of the
first blood flow channel.
6. The device of claim 1, wherein the first wall of the first blood
flow channel is the floor of the first blood flow channel.
7. The device of claim 1, wherein the height of the first blood
flow channel is between about 10 and 100 microns.
8. The device of claim 1, wherein the membrane thickness is between
about 10 and about 50 microns.
9. The device of claim 1, wherein the length of the first oxygen
flow channel and the first blood flow channel is between about 1 mm
and about 50 mm.
10. The device of claim 1, where the width of the first blood flow
channel is between about 100 microns and 200 microns.
11. The device of claim 1, wherein the membrane is permeable to
oxygen and carbon dioxide.
12. The device of claim 1, wherein the walls of the first blood
flow channel are coated with an anticoagulant.
13. The device of claim 1, wherein the device includes a second
blood flow channel separated from the first oxygen flow channel by
a second permeable membrane.
14. A method for oxygenating deoxygenate blood, the method
comprising: providing a microfluidic device comprising a first
polymer layer defining a first oxygen flow channel; a second
polymer layer defining a first blood flow channel, the first blood
flow channel further comprising at least one passive mixing element
formed in or on a surface of the first blood flow channel; and a
membrane separating the first oxygen flow channel and the first
blood flow channel, the membrane allowing communication between the
first oxygen flow channel and the first blood flow channel;
introducing partially deoxygenated blood into a proximal end of the
microfluidic device; flowing oxygen through the first oxygen flow
channel; flowing the partially deoxygenated blood through the first
blood flow channel; and receiving oxygenated blood at a distal end
of the microfluidic device.
15. The method of claim 14, further comprising: collecting
partially deoxygenated blood from a patient; flowing the partially
deoxygenated blood through the first blood flow channel to
reoxygenate the blood; and returning the reoxygenated blood to the
patient.
16. The method of claim 15, further comprising removing carbon
dioxide from the partially deoxygenated blood as the partially
deoxygenated blood flows through the first blood flow channel.
17. The method of claim 14, further comprising flowing oxygen
through the first oxygen flow channel from a first direction.
18. The method of claim 14, further comprising flowing blood
through the first blood flow channel in a second direction opposite
to the first direction.
19. The method of claim 14, further comprising flowing the blood
through the first blood flow channel at 4-5 L/min.
20. The method of claim 14, further comprising transferring oxygen
into the blood at a rate of about 150-200 mL/min.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This application claims priority from Provisional U.S.
Patent Application 61/567,104, filed Dec. 5, 2011, incorporated
herein by reference in its entirety.
BACKGROUND OF THE DISCLOSURE
[0002] Blood oxygenation systems are used for short term
respiratory support, such as during coronary artery bypass graft
surgeries or for acute respiratory distress syndrome patients. In
current systems, blood is oxygenated by pumping oxygen through an
inner, hollow fiber pumping blood though a larger, outer fiber that
encapsulates the inner fiber. The walls of the inner fiber are
permeable to oxygen and allow for the oxygenation of blood near the
inner fiber. Current oxygenation systems maintain a laminar blood
flow, only allowing the oxygenation of red blood cells within a
close proximity of the permeable membrane.
SUMMARY OF THE DISCLOSURE
[0003] According to one aspect of the disclosure, a microfluidic
oxygenation device includes a first polymer layer defining a first
oxygen flow channel. The device also includes a second polymer
layer defining a first blood flow channel. The first blood flow
channel overlaps the first oxygen flow channel, and the two
channels are separated by a permeable membrane that allows
communication between the channels at overlapping portions.
Additionally, first blood flow channel further includes at least
one passive mixing element along at least one wall. The passive
mixing element is configured to redistribute a fluid flowing
through the first blood flow channel within the channel.
[0004] In some implementations, the passive mixing element is one
of a straight ridge, an angled ridge, a chevron canal, a dome, a
cone, a pit or a post. In some implementations, a first fluid, such
as oxygen, flows through the first oxygen flow channel and a second
fluid, such as blood, flows through the first blood flow
channel.
[0005] In some implementations, the height or depth of the passive
mixing element is less than about 30% of the height of the first
blood flow channel, and the passive mixing elements are
incorporated into the floor of the first blood flow channel. In
other implementations, the height of the first blood flow channel
is between about 10 and 100 microns and the membrane thickness is
between about 10 and about 50 microns. In yet other
implementations, the length of the first oxygen flow channel and
the first blood flow channel is between about 1 mm and 50 mm and
the width is between about 100 microns and 200 microns.
[0006] In other implementations, the membrane is permeable to
oxygen and carbon dioxide. In yet other implementations, the walls
of the first blood flow channel are coated with an anticoagulant.
In yet other implementations, the device includes a second blood
flow channel separated from the first oxygen flow channel by a
second permeable membrane.
[0007] According to another aspect of the disclosure, a method for
oxygenating deoxygenate blood includes providing a microfluidic
device comprising a first polymer layer defining a first oxygen
flow channel and a second polymer layer defining a first blood flow
channel. The first blood flow channel also includes at least one
passive mixing element. A membrane separates the first oxygen flow
channel and the first blood flow channel and allows communication
between the first oxygen flow channel and the first blood flow
channel. The method also includes introducing partially
deoxygenated blood into a proximal end of the microfluidic device,
and flowing the partially deoxygenated blood through the device.
Additionally, the method includes flowing oxygen through the first
oxygen flow channel. Finally, oxygenated blood is received at a
distal end of the microfluidic device.
[0008] In some implementations, the method also includes collecting
partially deoxygenated blood from a patient, flowing the partially
deoxygenated blood through the first blood flow channel to
reoxygenate the blood, and returning the reoxygenated blood to the
patient. In other implementations, the method further includes
removing carbon dioxide from the partially deoxygenated blood as
the partially deoxygenated blood flows through the first blood flow
channel.
[0009] In yet other implementations, the method also includes
flowing oxygen through the first oxygen flow channel from a first
direction, and flowing blood through the first blood flow channel
in a second direction opposite to the first direction. In some
implementations, the blood is flowed through the first blood flow
channel at 4-5 L/min and oxygen is transferred to the blood at a
rate of about 150-200 mL/min.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The skilled artisan will understand that the figures,
described herein, are for illustration purposes only. It is to be
understood that in some instances various aspects of the described
implementations may be shown exaggerated or enlarged to facilitate
an understanding of the described implementations. In the drawings,
like reference characters generally refer to like features,
functionally similar and/or structurally similar elements
throughout the various drawings. The drawings are not necessarily
to scale, emphasis instead being placed upon illustrating the
principles of the teachings. The drawings are not intended to limit
the scope of the present teachings in any way. The system and
method may be better understood from the following illustrative
description with reference to the following drawings in which:
[0011] FIG. 1A is an isometric view of a device for oxygenating
blood, according to one illustrative implementation of the present
disclosure;
[0012] FIG. 1B is a cut-away view of a device for oxygenating
blood, according to one illustrative implementation of the present
disclosure;
[0013] FIG. 1C is an end view of a device of oxygenating blood as
depicted in FIG. 1, according to one illustrative implementation of
the present disclosure;
[0014] FIG. 2 is a cross-sectional view illustrating the flow
patterns of blood in a blood oxygenation device without passive
mixing elements, according to one illustrative implementation of
the present disclosure;
[0015] FIG. 3 is a cross-sectional view illustrating the flow
patterns of blood in a blood oxygenation device with passive mixing
elements as depicted in FIGS. 1A-1C, according to one illustrative
implementation of the present disclosure;
[0016] FIGS. 4A-J are top and isometric view of exemplary passive
mixing elements of a blood oxygenation device as depicted in FIG.
1, in accordance with an illustrative implementation of the present
disclosure; and
[0017] FIG. 5 is a flow chart of a method for oxygenating
deoxygenated blood with a blood oxygenation device as depicted in
FIG. 1, in accordance with an illustrative implementation of the
present disclosure.
DETAILED DESCRIPTION
[0018] The various concepts introduced above and discussed in
greater detail below may be implemented in any of numerous ways, as
the described concepts are not limited to any particular manner of
implementation. Examples of specific implementations and
applications are provided primarily for illustrative purposes.
[0019] The present system described herein generally relates to a
system and method for oxygenating blood. Accordingly, in various
implementations, the disclosure relates to oxygenating blood by
passively mixing the blood as it flows through the blood
oxygenation device. In certain implementations, the device includes
a plurality of passive elements on one wall of the device to mix
the flowing blood.
[0020] FIGS. 1A and 1B show an isometric view of a blood
oxygenation device 100 and a cutaway view thereof. Described in
greater detail below, but briefly, the device 100 includes a first
flow channel 101 separated from a second flow channel 102 by a gas
permeable membrane 103. The floor 105 of the second flow channel
102 includes a passive mixing element 106. The flow channels 101
and 102 are fabricated within a polymer substrate 104.
[0021] As illustrated in FIGS. 1A and 1B and discussed above,
device 100 includes a first flow channel 101 and second flow
channel 102 fabricated within a polymer substrate 104. In some
implementations, the polymer substrate 104 is a thermoplastic, such
as polystyrene or polyimide, biodegradable polyesters, such as
polycaprolactone (PCL), or soft elastomers such as polyglycerol
sebacate (PGS). In other implementations, the substrate 104 is
polydimethylsiloxane (PDMS), poly(N-isopropylacrylamide). In yet
other implementations, the substrate 104 includes non-polymer
materials such as, but not limited to, ceramics; metals; glasses;
nanotubes or nanowires formed from, for example, carbon or zinc
oxide; or other non-polymer materials.
[0022] In some implementations, the device 100 and the passive
mixing elements 106 are fabricated in the substrate 104 using, for
example, photolithographic techniques, injection molding, direct
micromachining, deep RIE etching, hot embossing, or any
combinations thereof.
[0023] The first flow channel 101 communicates with the second flow
channel 102 via the membrane 103. In some implementations, the
membrane 103 is permeable or semi-permeable to ions, molecules,
cells or any combination thereof. For example, the membrane 103 may
allow for oxygen to pass from the first flow channel 101 to the
second flow channel 102 and carbon dioxide to pass from the second
flow channel 102 to the first flow channel 101. However, in some
implementations, the membrane 103 is not permeable to red blood
cells. In some implementations, the membrane 103 is fabricated from
a semi-porous or porous material, such as polyethersulfone or PDMS.
In other implementations, the membrane 103 is created by
electrospinning a polymer to create a flexible, porous polymer
mesh.
[0024] The first flow channel 101 and the second flow channel 102
of device 100 run substantially parallel to one another, and, as
described above, are separated by the membrane 103 at overlapping
portions. In some implementations, the first flow channel 101
includes three smooth walls, with the fourth wall being the
membrane 103. In other implementations, the device 100 includes
additional flow channels to the left, right, and/or above the first
flow channel 101. In some of these implementations the first flow
channel 101 is also separated from these additional flow channels
by a permeable membrane 103. In other implementations, the first
flow channel is configured for the flow of a gas. For example,
oxygen may be flowed through the first flow channel 101. In other
implementations, the first flow channel 101 is configured to flow a
liquid. For example, the flow first flow channel may be configured
to flow blood.
[0025] The second flow channel 102 includes at least one passive
mixing element 106 along at least one wall of the channel. In the
implementation of device 100, the floor 105 includes passive mixing
elements 106(1)-106(n). In other implementations, any wall of the
first or second flow channel can include a passive mixing element
106. In some implementations, the floor, or other wall(s) that
include a passive mixing element 106, is replaceable, such that
different configurations of passive mixing elements can be used for
different fluids. In yet other implementations the device 100, or
components thereof, is disposable.
[0026] As described below, in some implementations, the passive
mixing elements include a plurality of ridges, channels,
protrusions, or any combination thereof. In some implementations
the passive mixing elements 106(1)-106(n) span the entire length of
a flow channel. In other implementations, the mixing elements 106
cover only a sub-portion of the total length of a flow channel 102.
In yet other implementations, the passive mixing elements
106(1)-106(n) are grouped together. For example, the fluid flow
channel 102 may contain a first type of passive mixing element 106
along a first portion of the flow channel 102 and then a second
type of passive mixing element 106 along a second portion of the
flow channel 102.
[0027] FIG. 1C illustrates an end view of device 100. In some
implementations, the device 100 is fabricated as a top component
104(b) and a bottom component 104(b) that are fabricated separately
and assembled to form device 100. In some implementations, the
components 104(a), 104(b), and the membrane 103 are attached to one
another with an adhesive. For example, the components of device 100
can be bound together with a chemical adhesive, plasma bonding,
and/or by clamping the components together. In other
implementations, the device 100 is fabricated as a single,
continuous unit. For example, device 100 can be created by
injection molding. In yet other implementations, the top portion
104(b) and the bottom portion 104(a) are formed by injection
molding. In some implementations, after the device 100 is
fabricated the channels are coated with an anticoagulant. In other
implementations, the anticoagulant is embedded in the polymer
substrate 104.
[0028] In some implementations the height or depth of a passive
mixing element 106 is between about 5% and about 10%, between about
10% and about 20%, or between about 20% and 30% of the total height
of the flow channel 102. In some implementations, each passive
mixing element in a channel is the same height or depth. While in
other implementations, the height or depth of the passive mixing
elements changes along the length of the flow channel 102.
[0029] In some implementations, the width, height, and length of
the first flow channel 101 and second flow channel 102 are the
same. In other implementations, one or all of the dimensions
between different flow channels is different. In some
implementations, the height of the flow channels is between about
10 microns and 25 microns, between about 25 microns and 50 microns,
or between about 50 microns and 100 microns. In some
implementations the thickness of the membrane 103 is between about
10 microns and 25 microns, between about 25 microns and 50 microns,
or between about 50 microns and 100 microns. In some
implementations, the length of the flow channels is between about 1
mm and 10 mm, between about 10 mm and 50 mm, or between about 50 mm
and 100 mm and the width is between about 100 microns and 200
microns, between 200 microns and 500 microns, or between about 500
microns and 1 cm.
[0030] FIG. 2 illustrates how fluid may flow through a blood
oxygenation device without passive mixing elements similar. FIG. 2
illustrates a blood oxygenation device 201 without passive mixing
elements along the floor 105(b). In this example, oxygen flows
through the first flow channel 201 as deoxygenated blood (white
circles) flows through the second flow channel 202. The blood in
the second flow channel 201 flows in a laminar pattern 203. The
blood cells become oxygenated (gray circles) as they flow
substantially close to the membrane 204. In some implementations,
because oxygen diffusion can only occur at distances substantially
close to the membrane 204, the portion of blood flowing along the
floor of the second flow channel 202 may never become
oxygenated.
[0031] In contrast, FIG. 3 illustrates how blood flows through a
blood oxygenation device 300 similar to the blood oxygenation
device 100. The floor 105 of device 300 includes a number of
passive flow elements 106. These passive flow elements 106 create
non-laminar flow 301 in the fluid of channel 102. In some
implementations this creates chaotic flow in channel 102. For
example, in some implementations, the passive mixing elements 106
drive fluid from the bottom of the fluid flow channel 102 towards
the membrane 103. In some implementations, the passive mixing
elements 106 create a rotational flow within in the flow channel.
For example, the passive mixing elements 106 may create a rifling
effect that causes the fluid to swirl as it flows down the flow
channel 102. In some implementations, the device 100 induces mixing
within a fluid without inducing mechanical trauma to the components
of the fluid. For example, the passive mixing elements 106 of
device 100 may drive blood towards the membrane 103 without causing
the red blood cells to hemorrhage or clot.
[0032] As illustrated in FIG. 3, the device 300, with the passive
mixing elements 106, is able to fully oxygenate the blood over a
shorter span of the device's length when compared to device 200
that does not include a passive mixing element 106. This allows for
a shorter channel, and therefore allows the device to be primed
with less blood than a channel without such passive mixing
elements.
[0033] FIGS. 4A-J show a top and isometric view of possible,
non-limiting examples of passive mixing elements 106. FIGS. 4A and
4B illustrate an alternating herringbone pattern. The design
consists of a herringbone pattern wherein the center of the
herringbone pattern shifts from one side of the flow channel to the
other through the length of the flow channel 102. In some
implementations, the alternating herringbone pattern causes the
fluid in the flow channel to enter the flow channel and begin
rotating in a first direction. Then, when the flowing fluid
encounters a shifted herringbone pattern, the fluid is forced to
rotate in a direction opposite to the first rotational direction.
For example, the fluid may enter the channel 102 flowing in a
laminar fashion, and then alternatingly switch between clockwise
and counter clockwise rotations as the fluid encounters
consecutive, offset herringbone patterns. In some implementations,
the number of chevrons per herringbone pattern and/or the number of
groupings is configured to create a specific level of mixing over a
given length of the device 100. In some implementations, the
herringbone pattern does not alternate, but is constant along the
duration of the flow channel. In some of these implementations the
center of the herringbone patterns is in the center of the channel,
while in other implementations the center of the pattern is
off-center with respect to the channel.
[0034] As illustrated in FIGS. 4C and D, in some implementations,
the mixing of a fluid is created with slanted ridges. Similar to
the herringbone patter described above, in some implementations the
slanted ridge pattern also creates a swirling rotation of the fluid
that drives fluid from the bottom of the fluid flow channel towards
the permeable membrane 103. In some implementations, the angle of
the slanted ridge and the herringbone patter is between about 35
and about 55 degrees. In some implementations, the spacing between
the ridges is between about 50 microns and about 100 microns,
between about 100 microns and 150 microns, or between about 150 and
about 200 microns. In some implementations, the spacing of the
ridges is 2.pi./(the width of the channel), such that the diameter
of the induced rotation is less than the width or depth of the
channel. In some implementations, the ridges of the above
implementations are rounded.
[0035] In yet other implementations, the passive mixing elements
106 are designed to create vortices and other high and low pressure
areas which drive the fluid towards the membrane 103. For example,
FIGS. 4E and 4F, like the illustrative implementation of FIG. 3,
include a plurality of ridges. In some implementations, the ridges
are spaced between about 20 microns and about 50 microns, between
about 50 microns and 100 microns or between about 100 microns and
500 microns.
[0036] In some implementations, the passive mixing elements can be,
but are not limited to, posts, mounds, ramps, pits, cones or any
combination thereof. FIGS. 4G-4J illustrate a possible post and
mound implementation. In the implementation illustrated in FIGS. 4G
and 4H, each row of posts is off set from the previous row. This
causes the fluid to mix laterally in addition to driving fluid
upwards. In other implementations, as illustrated in FIGS. 4I and
4J, the passive mixing elements are aligned with the passive mixing
elements in the previous row.
[0037] FIG. 5 is a flow chart of a method 500 for oxygenating blood
with a microfluidic device. First, a microfluidic device is
provided (step 501). Then, partially deoxygenated blood is
introduced into a proximal end of the microfluidic device (step
502). The partially deoxygenated blood is flowed through a first
channel of the microfluidic device (step 503), and oxygen is flowed
through a second channel of the microfluidic device (step 504).
Finally, oxygenated blood is collected from a distal end of the
microfluidic device (step 505).
[0038] As set forth above, and referring to FIG. 1, the method 500
for oxygenating partially deoxygenated blood begins with providing
a microfluidic device (step 501). In some implementations, the
microfluidic device is similar to device 100 described above. In
other implementations, the microfluidic device includes a plurality
of oxygen channels and/or a plurality of blood flow channels. In
yet other implementations, the microfluidic device is a array of
devices similar to device 100. In some implementations, the device
is configured to allow for about 500-1000 mL/min, about 1-4 L/min,
or about 4-5 L/min of blood flow. In some implementations, the
device is configured to transfer oxygen into the blood at a rate of
about 160 to about 200 mL/min.
[0039] Next, the method 500 of oxygenating blood continues with the
introduction of partially deoxygenated blood into a proximal end of
the microfluidic device (step 502). In some implementations, the
blood is directly collected form a patient and introduced into the
device. For example, the device may be part of a heart-lung bypass
system that oxygenates blood during surgery. In other
implementations, the blood is collected, stored, and then
oxygenated at a later time. For example, the blood may be collected
during a blood drive and then oxygenated prior to being transfused
into a patient. In some implementation, the blood is actively
pumped through the device by an external pump, and in other
implementations the blood is pumped through the device by the
patient's heart.
[0040] The method 500 continues by flowing the partially
deoxygenated blood through a first blood flow channel (step 503).
As described above, the device includes at least one passive mixing
element that inducing mixing within the channel as the blood
travels the length of the device. In some implementations, the
blood is thinned with a blood thinning agent such as the drug
Coumadin or Heparin. In some implementations, the walls of the
blood flow channels are coated with an anticoagulant.
[0041] Responsive to flowing blood through the first blood flow
channel, the method 500 continues by flowing oxygen through a first
oxygen flow channel (step 504). Referring to FIG. 1, the blood flow
channel and oxygen flow channel are separated by a permeable
membrane. Oxygen diffuses through the membrane, oxygenating the
blood as it flows down the length of the channel. In some
implementations, the blood is continually mixed within the channel
by the passive mixing elements similar to those described above. In
some implementations, the continual mixing allows a given volume of
deoxygenated blood to be oxygenated more efficiently by continually
exposing different red blood cells to the region near the membrane
where oxygen diffusion can occur. In other implementations, the
membrane is also porous to carbon dioxide, and the carbon dioxide
initially within the deoxygenated blood diffuses into the oxygen
flow channel. In yet other implementations, the oxygen and blood
are flowed through the microfluidic device starting at different
ends. For example, the blood may enter the device at a proximal end
and the oxygen may enter the device at a distal end of the
device.
[0042] The method 500 continues, with the collection of the
oxygenated blood at a distal end of the microfluidic channel. In
some implementations, the oxygenated blood is transfused directly
back into the patient from which it was collected. In other
implementations, the blood is collected and stored for later
transfusion or experimentation.
* * * * *